Guide To Buying Double And Triple Glazing

Over the years, more and more homeowners have had double glazed units installed in their homes to replace their old windows and doors with a view to reducing heat loss and cutting down noise from outside. However, there are still a lot of homeowners in the UK that have retained the single-pane glass in either their softwood or hardwood window frames and doors. Furthermore, it is only in recent years that new-build homes have had to have double-glazed windows and doors fitted as standard as we seek to become more energy efficient and environmentally friendly.

If you have made the decision to replace your old windows and doors with either double or triple glazed ones, you will find that there are a huge number of companies out there that specialize in the manufacture, supply and installation of replacement window units and doors. From a customer’s perspective, the more choice that you have the better but, equally, it can be a little confusing. Therefore, we hope that this guide to buying double or triple glazed windows and doors is of benefit. 

Before we discuss the options available to you in relation to buying double or triple glazed windows and doors we thought that you would find it useful to know something about things like Building Regulations, Planning Permission and u-Values.  

Building Regulations

The insulation efficiency of glazed doors and windows in buildings is worked out by using a u-Value. The lower the u-Value, the more efficient they are are at keeping a property warm by reducing the amount of cold air from outside getting into the home and reducing the amount of warm air in the property escaping.

Below we detail the current requirements for private dwellings that were introduced in recent years by the Government.

a - The Building Regulations 2010 - Amendments to the Approved Document LIB; Conservation of fuel and power in existing dwellings (2010 edition) published November 2013, coming into effect April 2014.

Windows, roof windows and roof lights - u-Value 1.6W/m2K

Doors - u-Value 1.8W/m2K

b - The Building Regulations 2010 - Approved Document L1A: Conservation of fuel and power in new dwellings, 2013 edition

  • Windows, roof windows, glazed roof lights and glazed doors - u-Value 1.4W/m2K
  • Semi-glazed doors - u-Value 1.2W/m2K

Therefore, you will need to make sure that any replacement windows and glazed doors meet the above minimum requirements.

Planning Permission

Planning permission is not normally required for replacement windows and doors as long as certain criteria are met. Such permission would be required if the local council issued an Article 4 Direction that withdrew permitted development rights or you would need listed building consent if you live in such a property.


Under the Building Regulations section above, we provided you with information about u-Values relating to glazed windows and doors. We thought you would find it interesting to know what the maximum u-Values are for certain other parts of new built properties in comparison to glazed windows and doors: -

External walls - 0.18W/m2K
Roof - 0.13W/m2K
Floor - 0.13W/m2K

As you can see, there is a significant difference. Therefore, it would make sense that, as well as having replacement windows and doors fitted, other parts of your home are well insulated to maximize the retention of heat in your property. So, you should also consider the likes of loft and cavity wall insulation. It is also worth pointing out that a window with single panes of glass has a u-Value of over 5.00W/m2K.

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